CN102511069A - Permanent magnet and manufacturing method for permanent magnet - Google Patents

Permanent magnet and manufacturing method for permanent magnet Download PDF

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Publication number
CN102511069A
CN102511069A CN201180003903XA CN201180003903A CN102511069A CN 102511069 A CN102511069 A CN 102511069A CN 201180003903X A CN201180003903X A CN 201180003903XA CN 201180003903 A CN201180003903 A CN 201180003903A CN 102511069 A CN102511069 A CN 102511069A
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permanent magnet
magnet
sintering
organo
metallic compound
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Inventor
尾关出光
久米克也
平野敬祐
大牟礼智弘
太白启介
星野利信
尾崎孝志
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Zhongjinchuan Packaging Industry Co ltd
Nitto Denko Corp
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Zhongjinchuan Packaging Industry Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/16—Metallic particles coated with a non-metal
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/005—Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0572—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes with a protective layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/06—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder
    • H01F1/08—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
    • H01F1/086—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together sintered
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0293—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets diffusion of rare earth elements, e.g. Tb, Dy or Ho, into permanent magnets

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  • Power Engineering (AREA)
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  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
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  • Powder Metallurgy (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)

Abstract

Disclosed are a permanent magnet and a manufacturing method for the permanent magnet in which trace amounts of Dy or Tb can efficiently be segregated to the grain boundaries of a magnet, and which provides sufficient improvement in the magnetic coercive force by Dy or Tb while reducing the amount of Dy or Tb used. An organometallic compound solution, to which an organometallic compound represented by the formula M-(OR)x has been added, is added to a fine powder of a pulverized neodymium magnet, and the organometallic compound is uniformly deposited on the surface of the neodymium magnet grains. Afterwards, calcination in hydrogen is carried out by retaining a molded article, formed by powder compacting, in a hydrogen atmosphere for several hours at 200 -900 . Afterwards, a permanent magnet is manufactured by sintering. (In the formula, M is Dy or Tb, R is a substituent group comprising a hydrocarbon, and can be a straight chain or a branched chain. x is an arbitrary integer.)

Description

The manufacturing approach of permanent magnet and permanent magnet
Technical field
The present invention relates to the manufacturing approach of permanent magnet and permanent magnet.
Background technology
In recent years, the permanent magnet motor in PHEV, hard disk drive etc., using requires miniaturization and, high-output powerization and high efficiency.And, when in above-mentioned permanent magnet motor, realizing miniaturization and, high-output powerization and high efficiency,, require further to improve magnetic characteristic for the permanent magnet that is embedded in the permanent magnet motor.In addition, as permanent magnet, ferrite lattice, Sm-Co base magnet, Nd-Fe-B base magnet, Sm are arranged 2Fe 17N xThe permanent magnet that the permanent magnet that the Nd-Fe-B base magnet that base magnet etc., particularly residual magnetic flux density are high is used as permanent magnet motor uses the high Nd-Fe-B base magnet of residual magnetic flux density to use as permanent magnet motor uses.
At this,, generally use powder sintering as the manufacturing approach of permanent magnet.At this, in the powder sintering,, and utilize jet pulverizer (dry type pulverizing) to carry out fine pulverizing and make ferromagnetic powder at first with the raw material coarse crushing.Then, this ferromagnetic powder is put into mould, drawing is required shape when applying magnetic field from the outside.Then, make at predetermined temperature (for example, the Nd-Fe-B base magnet is 800 ℃～1150 ℃) sintering through the solid shape ferromagnetic powder that will be configured as required form.
The prior art document
Patent documentation
Patent documentation 1: No. 3298219 communique of Japan Patent (the 4th page, the 5th page)
Summary of the invention
On the other hand, there is the low problem of heat resisting temperature in Nd base magnet such as Nd-Fe-B.Therefore, the Nd base magnet is being used under the situation of permanent magnet motor, the coercive force and the residual magnetic flux density of magnet slowly descend with this motor Continuous Drive the time.In addition, also produce irreversible demagnetization.Therefore, the Nd base magnet is used under the situation of permanent magnet motor,, adds high Dy (dysprosium) of magnetic anisotropy or Tb (terbium) coercive force with further raising magnet in order to improve the thermal endurance of Nd base magnet.
At this, as the method for adding Dy or Tb, the past have the surface that makes Dy or Tb be attached to sintered magnet and the grain boundary diffusion method that spreads and respectively manufacturing with principal phase and the corresponding powder of grain boundary and mix two alloyages of (doing mixed).The former is effective to the magnet of tabular or small pieces, and the diffusion length that still in large-scale magnet, has Dy or Tb can not extend to the shortcoming of inner grain boundary phase.The latter is owing to make magnet with two kinds of alloy blend, thereby so Dy or Tb be diffused into intragranular and have the shortcoming in (existing partially) partially in the grain boundary place.
Therefore in addition, Dy and Tb are rare metals, and the place of production is also limited, even degree seldom, also expect Dy or Tb are suppressed with respect to the use amount of Nd.In addition, when adding Dy or Tb in a large number, also there is the problem of the residual magnetic flux density decline of expression magnet strength.Therefore, expectation is the grain boundary place partially through Dy or the Tb that makes trace effectively, and under the situation that does not reduce residual magnetic flux density, significantly improves the coercitive technology of magnet.
The present invention foundes in order to eliminate said existing issue, and its purpose is to provide through in ferromagnetic powder, adding M-(OR) x(in the formula; M is Dy or Tb; The substituting group of R for being made up of hydrocarbon can be straight or branched, and x is integer arbitrarily) organo-metallic compound that contains Dy or Tb of expression; Can the Dy of trace contained in the organo-metallic compound or Tb be configured to effectively partially the grain boundary place of magnet on ground, though and the use amount that reduces Dy or Tb can fully improve the manufacturing approach of coercitive permanent magnet and permanent magnet through Dy or Tb.
In order to realize said purpose, permanent magnet of the present invention is characterised in that, through following operation manufacturing: with the magnet raw material pulverizing is the operation of ferromagnetic powder, through adding M-(OR) in the ferromagnetic powder that obtains in said pulverizing x(in the formula; M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched; X is an integer arbitrarily) organo-metallic compound of expression; Make said organo-metallic compound be attached to the operation of the particle surface of said ferromagnetic powder, be formed into the operation of body and with the operation of said formed body sintering through the said ferromagnetic powder that particle surface is attached with said organo-metallic compound.
In addition, permanent magnet of the present invention is characterized in that, forms the metal of said organo-metallic compound, retrodeviates the grain boundary place that is said permanent magnet at sintering.
In addition, permanent magnet of the present invention is characterized in that, said structural formula M-(OR) xIn R be alkyl.
In addition, permanent magnet of the present invention is characterized in that, said structural formula M-(OR) xIn R be in the alkyl of carbon number 2～6 any one.
In addition, the manufacturing approach of permanent magnet of the present invention is characterized in that, comprises following operation: with the magnet raw material pulverizing is the operation of ferromagnetic powder, through adding M-(OR) in the ferromagnetic powder that obtains in said pulverizing x(in the formula; M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched; X is an integer arbitrarily) organo-metallic compound of expression; Make said organo-metallic compound be attached to the operation of the particle surface of said ferromagnetic powder, be formed into the operation of body and with the operation of said formed body sintering through the said ferromagnetic powder that particle surface is attached with said organo-metallic compound.
In addition, the manufacturing approach of permanent magnet of the present invention is characterized in that, said structural formula M-(OR) xIn R be alkyl.
In addition, the manufacturing approach of permanent magnet of the present invention is characterized in that, said structural formula M-(OR) xIn R be in the alkyl of carbon number 2～6 any one.
The invention effect
According to permanent magnet of the present invention,, also can make the Dy of interpolation or the grain boundary place that Tb is magnet partially effectively even the addition of Dy or Tb was than lacked in the past with said formation.As a result, can reduce Dy or Tb use amount, can suppress that residual magnetic flux density descends and can fully improve coercive force through Dy or Tb.In addition, compare and can more easily carry out decarburization with the situation of adding other organo-metallic compound, need not to worry since in the magnet behind the sintering contained carbon cause that the magnet characteristic descends, and can be with magnet integral body sintering densely.
In addition, according to permanent magnet of the present invention, Dy that magnetic anisotropy is high or Tb retrodeviate the grain boundary place that is magnet at sintering, therefore are the Dy at grain boundary place or the generation that Tb suppresses the reverse magnetic domain of grain boundary partially, can improve coercive force thus.In addition, therefore the addition of Dy or Tb can suppress the decline of residual magnetic flux density than lacked in the past.
In addition,,, use the organo-metallic compound that constitutes by alkyl, therefore can easily carry out the thermal decomposition of organo-metallic compound as the organo-metallic compound that adds in the ferromagnetic powder according to permanent magnet of the present invention.As a result, when for example before sintering, in hydrogen atmosphere, carrying out the calcining of ferromagnetic powder or formed body, can reduce the carbon amount in ferromagnetic powder or the formed body more reliably.Thus, can suppress to separate out α Fe in the principal phase of the magnet behind the sintering, can magnet integral body sintering densely can be prevented that coercive force from descending.
In addition, according to permanent magnet of the present invention, as the organo-metallic compound that adds in the ferromagnetic powder, therefore the organo-metallic compound that uses the alkyl by carbon number 2～6 to constitute can carry out the thermal decomposition of organo-metallic compound at low temperatures.As a result, when for example before sintering, in hydrogen atmosphere, carrying out the calcining of ferromagnetic powder or formed body, can carry out the thermal decomposition of organo-metallic compound to whole ferromagnetic powders or formed body integral body more easily.That is,, can reduce the carbon amount in ferromagnetic powder or the formed body more reliably through calcination processing.
In addition, according to the manufacturing approach of permanent magnet of the present invention, even with compared the addition that reduces Dy or Tb in the past, also can make the permanent magnet at the grain boundary place that the Dy that makes interpolation effectively or Tb be magnet partially.As a result, in the permanent magnet of making, can suppress residual magnetic flux density decline and fully improve coercive force through Dy or Tb.In addition, compare and can carry out decarburization more easily with the situation of adding other organo-metallic compound, need not to worry since in the magnet behind the sintering contained carbon cause the magnet characteristic to descend, and can be with magnet integral body sintering densely.
In addition,,, use the organo-metallic compound that constitutes by alkyl, therefore can easily carry out the thermal decomposition of organo-metallic compound as the organo-metallic compound that adds in the ferromagnetic powder according to the manufacturing approach of permanent magnet of the present invention.As a result, when for example before sintering, in hydrogen atmosphere, carrying out the calcining of ferromagnetic powder or formed body, can reduce the carbon amount in ferromagnetic powder or the formed body more reliably.Thus, can be suppressed in the principal phase of the magnet behind the sintering and separate out α Fe, can be with magnet integral body sintering densely, and can prevent that coercive force from descending.
In addition; Manufacturing approach according to permanent magnet of the present invention; As the organo-metallic compound that adds in the ferromagnetic powder, therefore the organo-metallic compound that uses the alkyl by carbon number 2～6 to constitute can carry out the thermal decomposition of organo-metallic compound at low temperatures.As a result, when for example before sintering, in hydrogen atmosphere, carrying out the calcining of ferromagnetic powder or formed body, can carry out the thermal decomposition of organo-metallic compound to whole ferromagnetic powders or formed body integral body more easily.That is,, can reduce the carbon amount in ferromagnetic powder or the formed body more reliably through calcination processing.
Description of drawings
Fig. 1 is the overall diagram of expression permanent magnet of the present invention.
Fig. 2 is with near the sketch map that amplifies expression the grain boundary of permanent magnet of the present invention.
Fig. 3 is the figure of the B-H loop of expression kicker magnet.
Fig. 4 is the sketch map of the domain structure of expression kicker magnet.
Fig. 5 is the key diagram of manufacturing process in first manufacturing approach of expression permanent magnet of the present invention.
Fig. 6 is the key diagram of manufacturing process in second manufacturing approach of expression permanent magnet of the present invention.
Fig. 7 is the figure that expression is carried out the situation of calcination processing in the hydrogen and do not carried out the variation of oxygen amount under the situation of calcination processing in the hydrogen.
Fig. 8 is the figure of the residual carbon amount in the permanent magnet of permanent magnet of expression embodiment 1～3 and comparative example 1～3.
Fig. 9 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 1.
Figure 10 is the SEM photo behind the sintering of permanent magnet of embodiment 1 and in the visual field identical with the SEM photo, draws the distribution of Dy element and the figure that obtains.
Figure 11 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 2.
Figure 12 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 3.
Figure 13 is the SEM photo behind the sintering of permanent magnet of embodiment 3 and in the visual field identical with the SEM photo, draws the distribution of Tb element and the figure that obtains.
Figure 14 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 1.
Figure 15 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 2.
Figure 16 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 3.
Figure 17 is the figure of the carbon amount in the permanent magnet change calcining heat condition of comparative example 4,5 of a plurality of permanent magnets represent to make with to(for) embodiment 4.
Embodiment
Below, the execution mode for the manufacturing approach of permanent magnet of the present invention and permanent magnet is specialized is elaborated with reference to accompanying drawing.
[formation of permanent magnet]
At first, the formation to permanent magnet 1 of the present invention describes.Fig. 1 is the overall diagram of expression permanent magnet 1 of the present invention.In addition, permanent magnet 1 shown in Figure 1 has cylindrical, and still, the shape of permanent magnet 1 changes according to the shape of the chamber that uses in being shaped.
As permanent magnet 1 of the present invention, for example use the Nd-Fe-B base magnet.In addition, coercitive Dy (dysprosium) or the Tb (terbium) that is used to improve permanent magnet 1 is to form the interface (grain boundary) of each Nd crystal grain of permanent magnet 1 partially and locates.In addition, the content of each composition is set at, Nd:25～37 weight %, Dy (or Tb): 0.01～5 weight %, B:1～2 weight %, Fe (electrolytic iron): 60～75 weight %.In addition, in order to improve magnetic characteristic, can contain a small amount of other element such as Co, Cu, Al, Si etc.
Particularly, permanent magnet 1 of the present invention, as shown in Figure 2, the surface applied Dy layer (or Tb layer) 11 through at the Nd crystal grain 10 that constitutes permanent magnet 1 makes Dy or Tb be the grain boundary place of Nd crystal grain 10 partially.Fig. 2 amplifies the figure of expression with the Nd crystal grain that constitutes permanent magnet 1 10.
As shown in Figure 2, permanent magnet 1 is made up of the Dy layer (or Tb layer) 11 on the surface of Nd crystal grain 10, coating Nd crystal grain 10.In addition, Nd crystal grain 10 is for example by Nd 2Fe 14The B intermetallic compound constitutes, and Dy layer 11 is for example by (Dy xNd 1-x) 2Fe 14The B intermetallic compound constitutes.
Below, use Fig. 3 and Fig. 4 that the coercitive mechanism that improves permanent magnet 1 through Dy layer (or Tb layer) is described.Fig. 3 is the figure of the B-H loop of expression kicker magnet, and Fig. 4 is the figure of the domain structure of expression kicker magnet.
As shown in Figure 3, the coercive force of permanent magnet, when under magnetized state, applying rightabout magnetic field, making magnetic polarization is the intensity in the required magnetic field of 0 (being magnetic reversal).Therefore, if can suppress magnetic reversal, then can obtain high-coercive force.In addition, in the magnetization process of magnet, exist based on the rotary magnetization of the rotation of magnetic moment and as the neticdomain wall that the neticdomain wall (comprising 90 ° of neticdomain walls and 180 ° of neticdomain walls) on magnetic domain border is moved and move.In addition, in the sintered body magnet such as the Nd-Fe-B of object of the present invention base, reverse magnetic domain is easy to generate in the near surface as the crystal grain of principal phase most.Therefore, among the present invention, locate to generate with Dy or Tb at the surface portion (shell) of the crystal grain of Nd crystal grain 10 and replace a part of Nd and the phase that obtains, suppress the generation of reverse magnetic domain.In addition, improving Nd 2F 14The effect aspect of the coercive force of B intermetallic compound (prevention magnetic reversal), Dy and Tb that magnetic anisotropy is high are effective element.
At this, among the present invention, the displacement of Dy, Tb, of the back, carry out through before the ferromagnetic powder that pulverizing is obtained is shaped, adding the organo-metallic compound that contains Dy (or Tb).Particularly; In the time will being added with the ferromagnetic powder sintering of the organo-metallic compound that contains Dy (or Tb); Disperse and evenly be attached to the Dy (or Tb) in this organo-metallic compound of particle surface of Nd magnet particle through wet type; Replace in the crystalline growth zone that diffuses into Nd magnet particle, forms Dy layer shown in Figure 2 (or Tb layer).As a result, as shown in Figure 4, Dy (or Tb) is the interface of Nd crystal grain 10 partially, thereby can improve the coercive force of permanent magnet 1.
In addition, particularly among the present invention of the back, will be by M-(OR) x(in the formula; M is Dy or Tb; The substituting group of R for being made up of hydrocarbon can be straight or branched, and x is integer arbitrarily) organo-metallic compound that contains Dy (or Tb) of expression is (for example; Ethanol dysprosium, normal propyl alcohol dysprosium, ethanol terbium etc.) add in the organic solvent, and under the wet type state, be mixed in the ferromagnetic powder.Thus, the organo-metallic compound that contains Dy (or Tb) is disperseed in organic solvent, and the organo-metallic compound that will contain Dy (or Tb) is attached to the particle surface of Nd magnet particle effectively.
At this, as satisfying said M-(OR) xThe organo-metallic compound of (in the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x is an integer arbitrarily) structural formula has metal alkoxide.Metal alkoxide is by formula M-(OR) n(M: metallic element, R: organic group, n: metal or semimetallic valence mumber) expression.In addition, as the metal or the semimetal that form metal alkoxide, can enumerate W, Mo, V, Nb, Ta, Ti, Zr, Ir, Fe, Co, Ni, Cu, Zn, Cd, Al, Ga, In, Ge, Sb, Y, lanthanide series etc.But, use Dy or Tb among the present invention especially.
In addition, the not special restriction of the kind of alkoxide for example can be enumerated: methoxide, ethylate, propylate, isopropoxide, butylate, the alkoxide of carbon number more than 4 etc.But, among the present invention of the back, consider from the purpose that suppresses residual carbon through low-temperature decomposition, use the low-molecular-weight alkoxide.In addition, the methoxide of carbon number 1, owing to be easy to decompose and be difficult to operation, therefore preferred especially ethylate as the alkoxide of carbon number contained among the R 2～6, methoxide, isopropoxide, propylate, the butylate etc. of using.That is, among the present invention, especially, as the organo-metallic compound that adds in the ferromagnetic powder, M-(OR) is used in expectation xThe organo-metallic compound of (in the formula, M is Dy or Tb, and R is an alkyl, can be straight or branched, and x is an integer arbitrarily) expression, more preferably M-(OR) xThe organo-metallic compound of (in the formula, M is Dy or Tb, and R is any one in the alkyl of carbon number 2～6, can be straight or branched, and x is an integer arbitrarily) expression.
In addition, if will under suitable calcination condition, calcine, can prevent that then Dy or Tb scattering and permeating (solid solution) are in Nd crystal grain 10 through the formed body that powder pressing forms.Thus, in the present invention,, also can make zone only be housing parts by Dy or Tb displacement though add Dy or Tb.As a result, as crystal grain whole (that is, whole), become the Nd of core as sintered magnet 2Fe 14The B intermetallic compound accounts for the state of high volume ratio mutually.Thus, can suppress the decline of the residual magnetic flux density (external magnetic field strength is 0 o'clock a magnetic flux density) of this magnet.
In addition, Dy layer (or Tb layer) 11 needs not to be the layer that only is made up of Dy compound (or Tb compound), also can be by the layer of Dy compound (or Tb compound) with the mixture formation of Nd compound.At this moment, through interpolation Nd compound, and form by the layer of Dy compound (or Tb compound) with the mixture formation of Nd compound.As a result, the liquid-phase sintering in the time of can promoting the sintering of Nd ferromagnetic powder.In addition, as the Nd compound that is added, expectation NdH 2, neodymium acetate hydrate, neodymium acetyl acetonate (III) trihydrate, 2 ethyl hexanoic acid neodymium (III), hexafluoro neodymium acetyl acetonate (III) dihydrate, isopropyl alcohol neodymium, neodymium phosphate (III) n hydrate, trifluoroacetyl neodymium acetate, TFMS neodymium etc.
In addition, as making Dy or Tb be the formation at the grain boundary place of Nd crystal grain 10 partially, can be to make the particle formula of interspersing that comprises Dy or Tb be present in the formation of the grain boundary of Nd crystal grain 10.Even such formation also can obtain same effect.In addition, Dy or Tb are the grain boundary place of Nd crystal grain 10 in which way partially, for example can confirm through SEM, TEM, three-dimensional atom probe method.
[manufacturing approach 1 of permanent magnet]
Below, use Fig. 5 that first manufacturing approach of permanent magnet 1 of the present invention is described.Fig. 5 is the key diagram of manufacturing process in first manufacturing approach of expression permanent magnet 1 of the present invention.
At first, manufacturing is by the ingot of Nd-Fe-B (for example, Nd:32.7 weight %, Fe (electrolytic iron): 65.96 weight %, the B:1.34 weight %) formation of predetermined score.Then, use bruisher or disintegrating machine etc. with the size of ingot coarse crushing for about 200 μ m.Perhaps, with the ingot dissolving, make thin slice through the thin-belt casting rolling legal system, and carry out mealization with the hydrogen comminuting method.
Then; The ferromagnetic powder that coarse crushing is obtained is essentially in the atmosphere that inert gases such as 0% nitrogen, Ar gas, He gas constitute in (a) oxygen content, perhaps (b) oxygen content is in the atmosphere that constitutes of inert gases such as 0.0001～0.5% nitrogen, Ar gas, He gas; It is broken to utilize jet pulverizer 41 to carry out micro mist; Obtain having the micropowder of the average grain diameter of (for example, 0.1 μ m～5.0 μ m) below the preliminary dimension.In addition, oxygen concentration is essentially 0%, is not limited to oxygen concentration and is entirely 0% situation, is meant the oxygen of the amount that also can contain the degree that forms oxide-film on the surperficial denier ground of micro mist.
On the other hand, make toward organo-metallic compound solution through adding in the broken micropowder that obtains of jet pulverizer 41 micro mists.At this, the organo-metallic compound that will contain Dy (or Tb) in advance adds in the organo-metallic compound solution and makes its dissolving.In addition, as the organo-metallic compound that is dissolved, expectation is used and is equivalent to M-(OR) xThe organo-metallic compound (for example, ethanol dysprosium, normal propyl alcohol dysprosium, ethanol terbium etc.) of (in the formula, M is Dy or Tb, and R is any one in the alkyl of carbon number 2～6, can be straight or branched, and x is an integer arbitrarily).In addition; The not special restriction of the amount of the organo-metallic compound that contains Dy (or Tb) that is dissolved; Preferably as previously mentioned, make that the content of Dy (or Tb) is 0.001 weight %～10 weight %, the more preferably amount of 0.01 weight %～5 weight % in the magnet behind sintering.
Then, in the micropowder that obtains through jet pulverizer 41 classifications, add above-mentioned organo-metallic compound solution.Thus, generate the powder of magnet raw material and the slurry 42 that organo-metallic compound solution mixes.In addition, carry out in the atmosphere that is added on inert gases formations such as nitrogen, Ar gas, He gas of organo-metallic compound solution.
Then, before the slurry that generates 42 is shaped, carries out drying through vacuumize etc. in advance, and take out dried ferromagnetic powder 43.Then, utilize building mortion 50 powder pressings to be predetermined shape dried ferromagnetic powder.In addition, powder pressing has and is filled into the damp process in the chamber after above-mentioned dried micropowder is filled into the dry process in the chamber and utilizes solvent etc. to form pulp-like, and illustration is used the situation of dry process among the present invention.In addition, organo-metallic compound solution can volatilize by the calcination stage after shaping.
As shown in Figure 5, building mortion 50 tools mould cylindraceous 51, dash 52 and go up towards 53 with respect to what mould 51 slided along the vertical direction equally down with respect to what mould 51 slided along the vertical direction, the space that is surrounded by them constitutes chamber 54.
In addition, in building mortion 50, pair of magnetic field generation coil 55,56 is configured in the upper-lower position of chamber 54, and the magnetic line of force is applied on the ferromagnetic powder 43 that is filled in the chamber 54.The magnetic field that applies for example is set at 1MA/m.
And, during the press forming of conducting powder end, at first, dried ferromagnetic powder 43 is filled in the chamber 54.Then, drive dash down 52 with on dash 53, along the direction of arrow 61 ferromagnetic powder 43 that is filled in the chamber 54 is exerted pressure, form.In addition, produce coil 55,56 edges arrow 62 directions parallel through magnetic field pressurization the time ferromagnetic powder 43 that is filled in the chamber 54 is applied pulsed magnetic field with compression aspect.Thus, make magnetic field along required direction orientation.In addition, make the direction of magnetic field orientating need consider to confirm by the permanent magnet 1 desired magnetic direction that ferromagnetic powder 43 is shaped.
In addition, during the use damp process, can when chamber 54 is applied magnetic field, inject slurry, and inject the way or injecting the initial strong magnetic field, magnetic field of the after-applied ratio of end and carry out wet forming.In addition, also can dispose magnetic field perpendicular to the mode of compression aspect and produce coil 55,56 to apply direction.
Then, will in hydrogen atmosphere, keep several hours (for example 5 hours) down, carry out calcination processing in the hydrogen thus through the formed body 71 that powder pressing forms at 200 ℃～900 ℃, more preferably 400 ℃～900 ℃ (for example 600 ℃).Hydrogen quantity delivered in the calcining is set at 5L/ minute.In this hydrogen in the calcination processing, thereby make the organo-metallic compound thermal decomposition reduce the so-called carbonization treatment of the carbon amount in the calcined body.In addition, in the hydrogen carbon amount of calcination processing in making calcined body be lower than 0.2 weight %, more preferably less than carrying out under the condition of 0.1 weight %.Thus, sintering processes that can be through after this can not reduce residual magnetic flux density and coercive force with permanent magnet 1 integral body sintering densely.
At this, in the formed body 71 after the calcination processing calcining in the described hydrogen, there is NdH 3Thereby, have the problem that combines with oxygen easily, still, in first manufacturing approach, formed body 71 after the hydrogen calcining not with situation that extraneous gas contacts under the sintering stated after transferring to, so do not need the dehydrogenation operation.Hydrogen release in the sintering in the formed body goes out.
Then, carry out sintering processes through formed body 71 sintering after the calcination processing calcining in the hydrogen.In addition, as the sintering method of formed body 71, except that general vacuum-sintering, also can use the pressure sintering of sintering under the state that formed body 71 is pressurizeed etc.For example, when carrying out sintering, be warmed up to about 800 ℃～about 1080 ℃ with predetermined programming rate, and kept about 2 hours through vacuum-sintering.During this period, carry out vacuum-sintering, vacuum degree is preferably set to 10 -4Below the Torr.Cooling is carried out heat treatment in 2 hours at 600 ℃～1000 ℃ more then.The result of sintering has made permanent magnet 1.
On the other hand, as pressure sintering, hot pressed sintering, high temperature insostatic pressing (HIP) (HIP) sintering, the synthetic sintering of superhigh pressure, gas pressurized sintering, discharge plasma (SPS) sintering etc. are for example arranged.But, when suppressing sintering the grain growth of magnet particle and suppress sintering after the warpage that produces in the magnet, the preferred use as the SPS sintering that carries out sintering along the single shaft pressure sintering of single shaft direction pressurization and through the energising sintering.In addition, when carrying out sintering through the SPS sintering, preferred: pressurization value is set at 30MPa, is warming up to 940 ℃ with 10 ℃/minute in the vacuum atmosphere below several Pa, keeps then 5 minutes.Cooling is carried out heat treatment in 2 hours at 600 ℃～1000 ℃ more then.And the result of sintering has made permanent magnet 1.
[manufacturing approach 2 of permanent magnet]
Below, use Fig. 6 that second manufacturing approach as another manufacturing approach of permanent magnet 1 of the present invention is described.Fig. 6 is the key diagram of manufacturing process in second manufacturing approach of expression permanent magnet 1 of the present invention.
In addition, the operation till generating slurry 42, identical with the manufacturing process in first manufacturing approach of using Fig. 5 to explain, therefore omit explanation.
At first, before the slurry that generates 42 is shaped, carries out drying through vacuumize etc. in advance, and take out dried ferromagnetic powder 43.Then, dried ferromagnetic powder 43 is kept several hours (for example 5 hours) in hydrogen atmosphere, under 200 ℃～900 ℃, more preferably 400 ℃～900 ℃ (for example 600 ℃), carry out calcination processing in the hydrogen thus.Hydrogen quantity delivered in the calcining is set at 5L/ minute.In this hydrogen in the calcination processing, thereby make residual organo-metallic compound thermal decomposition reduce the so-called carbonization treatment of the carbon amount in the calcined body.In addition, in the hydrogen carbon amount of calcination processing in making calcined body be lower than 0.2 weight %, more preferably less than carrying out under the condition of 0.1 weight %.Thus, sintering processes that can be through after this can not reduce residual magnetic flux density and coercive force with permanent magnet 1 integral body sintering densely.
Then, will in vacuum atmosphere, keep 1～3 hour down, and carry out dehydrogenation thus and handle through the pulverous calcined body 82 after the calcination processing calcining in the hydrogen at 200 ℃～600 ℃, more preferably 400 ℃～600 ℃.In addition, vacuum degree is preferably set to below the 0.1Torr.
At this, in the calcined body 82 after the calcination processing calcining in the described hydrogen, there is NdH 3Thereby, have the problem that combines with oxygen easily.
Fig. 7 is that expression will be carried out the Nd ferromagnetic powder after the calcination processing in the hydrogen and the Nd ferromagnetic powder that does not carry out calcination processing in the hydrogen when being exposed in the atmosphere of oxygen concentration 7ppm and oxygen concentration 66ppm respectively and the figure of the interior oxygen amount of corresponding ferromagnetic powder of open-assembly time.As shown in Figure 7, when carrying out that the ferromagnetic powder after the calcination processing is in being exposed to hyperoxia concentration 66ppm atmosphere in the hydrogen, the oxygen amount in the ferromagnetic powder rose to 0.8% with about 1000 seconds from 0.4%.In addition, even be exposed in the low oxygen concentration 7ppm atmosphere, the oxygen amount in the magnet also rose to identical 0.8% from 0.4% with about 5000 seconds.And, when Nd combines with oxygen, can cause residual magnetic flux density or coercive force to descend.
Therefore, in said dehydrogenation is handled, make the NdH in the calcined body 82 that generates through calcination processing in the hydrogen 3(activity degree is big) is with NdH 3(activity degree is big) → NdH 2(activity degree is little) direction progressively changes, and the activity degree of the calcined body 82 of activation through calcination processing in the hydrogen is descended.Thus, even will transfer in the atmosphere through the calcined body 82 after the calcination processing calcining in the hydrogen afterwards the time, can prevent that also Nd from combining with oxygen, thereby not reduce residual magnetic flux density and coercive force.
Then, pulverous calcined body 82 powder pressings that utilize building mortion 50 will carry out after dehydrogenation is handled are reservation shape.About the details of building mortion 50, same with the manufacturing process in first manufacturing approach of using Fig. 5 to explain, therefore omit explanation.
Then, carry out sintering processes with calcined body 82 sintering that are shaped.In addition, sintering processes and the first above-mentioned manufacturing approach are likewise carried out through vacuum-sintering, pressure sintering etc.About the details of sintering condition, same with the manufacturing process in first manufacturing approach of having explained, therefore omit explanation.And the result of sintering has made permanent magnet 1.
In addition; In the second above-mentioned manufacturing approach; Pulverous magnet particle is carried out calcination processing in the hydrogen; Therefore compare with the magnet particle after being shaped being carried out in the hydrogen said first manufacturing approach of calcination processing, have the advantage that more easily to carry out the thermal decomposition of organo-metallic compound whole magnet particles.That is, compare, can reduce the carbon amount in the calcined body more reliably with said first manufacturing approach.
On the other hand, in first manufacturing approach, formed body 71 is calcined the back and with under the situation that extraneous gas contact is not being transferred to sintering in hydrogen, so does not need the dehydrogenation operation.Therefore, compare, can simplify manufacturing process with said second manufacturing approach.But, even in said second manufacturing approach, in hydrogen calcining back not with situation that extraneous gas contacts under when carrying out sintering, do not need the dehydrogenation operation yet.
Embodiment
Below, describe when comparing for embodiments of the invention with comparative example.
(embodiment 1)
The alloy composition of the neodium magnet powder of embodiment 1; Than the ratio that has improved Nd based on the mark (Nd:26.7 weight %, Fe (electrolytic iron): 72.3 weight %, B:1.0 weight %) of stoichiometric composition; For example, set Nd/Fe/B=32.7/65.96/1.34 in weight %.In addition, in the neodium magnet powder that obtains in pulverizing, add 5 weight % normal propyl alcohol dysprosiums as the organo-metallic compound that contains Dy (or Tb).In addition, calcination processing keeps carrying out in 5 hours at 600 ℃ in hydrogen atmosphere through the ferromagnetic powder before will being shaped.And the hydrogen quantity delivered in the calcining is set at 5L/ minute.In addition, the sintering of the calcined body after the shaping carries out through the SPS sintering.In addition, other operation is and above-mentioned [manufacturing approach 2 of permanent magnet] same operation.
(embodiment 2)
The organo-metallic compound that adds is set at the ethanol terbium.Other condition is identical with embodiment 1.
(embodiment 3)
The organo-metallic compound that adds is set at the ethanol dysprosium.Other condition is identical with embodiment 1.
(embodiment 4)
The sintering of the calcined body after the shaping replaces the SPS sintering to carry out through vacuum-sintering.Other condition and embodiment 1 are same.
(comparative example 1)
The organo-metallic compound that adds is set at the normal propyl alcohol dysprosium, and does not carry out calcination processing in the hydrogen and sintering.Other condition and embodiment 1 are same.
(comparative example 2)
The organo-metallic compound that adds is set at the ethanol terbium, and does not carry out calcination processing in the hydrogen and sintering.Other condition and embodiment 1 are same.
(comparative example 3)
The organo-metallic compound that adds is set at the acetyl acetone dysprosium.Other condition and embodiment 1 are same.
(comparative example 4)
Calcination processing is carried out in He atmosphere not in hydrogen atmosphere.In addition, the sintering of the calcined body after the shaping replaces the SPS sintering to carry out through vacuum-sintering.Other condition and embodiment 1 are same.
(comparative example 5)
Calcination processing is carried out in vacuum atmosphere not in hydrogen atmosphere.In addition, the sintering of the calcined body after the shaping replaces the SPS sintering to carry out through vacuum-sintering.Other condition and embodiment 1 are same.
(comparative studies of the residual carbon amount of embodiment and comparative example)
Fig. 8 is the figure that representes the residual carbon amount [weight %] in the permanent magnet of permanent magnet of embodiment 1～3 and comparative example 1～3 respectively.
As shown in Figure 8, can find out that embodiment 1～3 compares with comparative example 1～3, can significantly reduce carbon amount residual in the magnet particle.Especially, among the embodiment 1～3, can make carbon amount residual in magnetite particle be lower than 0.2 weight %.
In addition; During with embodiment 1,3 and comparative example 1,2 comparisons; Although can find out and add identical organo-metallic compound, carry out the situation of calcination processing in the hydrogen and compare with the situation of not carrying out calcination processing in the hydrogen, can significantly reduce the carbon amount in the magnet particle.That is, can find out, make the organo-metallic compound thermal decomposition, can reduce the so-called carbonization treatment of the carbon amount in the calcined body through calcination processing in the hydrogen.As a result, can realize the whole dense sintering of magnet and prevent that coercive force from descending.
In addition, when embodiment 1～3 is compared with comparative example 3, can find out, add M-(OR) x(in the formula, M is Dy or Tb, the substituting group of R for being made up of hydrocarbon; Can be straight or branched; X is an integer arbitrarily) under the situation of the organo-metallic compound of expression, compare with the situation of adding other organo-metallic compound, can significantly reduce the carbon amount in the magnet particle.That is, can find out, through the organo-metallic compound that adds is set at M-(OR) xThe organo-metallic compound that (in the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x be an integer arbitrarily) represented can easily carry out decarburization in the calcination processing in hydrogen.As a result, can realize the whole dense sintering of magnet and prevent that coercive force from descending.In addition; Especially; If the organo-metallic compound that use the organo-metallic compound that is made up of alkyl, more preferably is made up of the alkyl of carbon number 2～6 is as the organo-metallic compound that adds; When then in hydrogen atmosphere, ferromagnetic powder being calcined, can carry out the thermal decomposition of organo-metallic compound at low temperatures.Thus, can more easily carry out the thermal decomposition of organo-metallic compound to whole magnet particles.
(the XMA surface analysis outcome research of the permanent magnet of embodiment)
Permanent magnet to embodiment 1～3 carries out the XMA surface analysis.Fig. 9 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 1.Figure 10 is the SEM photo behind the sintering of permanent magnet of embodiment 1 and in the visual field identical with the SEM photo, draws the distribution of Dy element and the figure that obtains.Figure 11 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 2.Figure 12 is the figure of the results of elemental analyses of SEM photo and grain boundary phase behind the sintering of permanent magnet of expression embodiment 3.Figure 13 is the SEM photo behind the sintering of permanent magnet of embodiment 3 and in the visual field identical with the SEM photo, draws the distribution of Tb element and the figure that obtains.
Like Fig. 9,11, shown in 12, in each permanent magnet of embodiment 1～3, detect the Dy of oxide or non-oxide form mutually from grain boundary.That is, can find out that in the permanent magnet of embodiment 1～3, Dy is diffused into principal phase mutually from grain boundary, in the surface portion of principal phase particle (shell), locate to form the phase that a part of Nd is obtained by the Dy displacement on the surface of principal phase particle (grain boundary).
In addition, in the distribution map of Figure 10, the part of white is represented the distribution of Dy element.With reference to SEM photo and the distribution map of Figure 10, the white portion of distribution map (being the Dy element) distributes (changing て distribution partially) partially around principal phase on ground.That is, can find out that in the permanent magnet of embodiment 1, Dy is the grain boundary place of magnet partially.On the other hand, in the distribution map of Figure 13, the part of white is represented the distribution of Tb element.With reference to SEM photo and the distribution map of Figure 13, the white portion of distribution map (being the Tb element) partially ground be distributed in principal phase around.That is, can find out that in the permanent magnet of embodiment 3, Tb is the grain boundary place of magnet partially.
Can find out from above result, in embodiment 1～3, can make Dy or Tb be the grain boundary place of magnet partially.
(the SEM photo comparative studies of embodiment and comparative example)
Figure 14 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 1.Figure 15 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 2.Figure 16 is the figure of the SEM photo behind the sintering of permanent magnet of expression comparative example 3.
In addition, when each SEM photo of embodiment 1～3 and comparative example 1～3 is compared, the residual carbon amount be a certain amount of below in embodiment 1～3 and the comparative example 1 of (for example, below the 0.2 weight %), basically by the principal phase (Nd of neodium magnet 2F 14B) 91 with seem to be white in color mottled grain boundary 92 permanent magnets that form behind the sintering mutually.In addition, also formed a spot of α Fe phase.Relative therewith, in the comparative example 2,3 of residual carbon amount than embodiment 1～3 and comparative example more than 1, except principal phase 91 and grain boundary mutually 92, also formation seems the α Fe phase 93 of black in color band shape in a large number.At this, α Fe is the material that residual carbide forms during by sintering.That is,, therefore resemble comparative example 2,3 like this in sintering circuit during the carbon containing thing in the also residual organo-metallic compound of high temperature, the formation carbide because the reactivity of Nd and C is very high.As a result, separate out α Fe in the magnet principal phase through formed carbide behind sintering, thereby significantly reduce the magnet characteristic.
On the other hand, in embodiment 1～3, as stated,, can make the organo-metallic compound thermal decomposition, can in advance the carbon that is contained be burnt and lose (reducing the carbon amount) through using suitable organo-metallic compound and carrying out calcination processing in the hydrogen.Especially; Temperature through will calcine the time is set at 200 ℃～900 ℃, more preferably 400 ℃～900 ℃; Can the carbon that contained be burnt and lose more than the necessary amount, can make the carbon amount that residues in the magnet behind the sintering be lower than 0.2 weight %, more preferably less than 0.1 weight %.And the carbon amount that residues in the magnet is lower than among the embodiment 1～3 of 0.2 weight %, in sintering circuit, forms carbide hardly, need not to worry to form a large amount of α Fe phases 93 as comparative example 2,3.As a result, like Fig. 9～shown in Figure 13, can make permanent magnet 1 integral body sintering densely through sintering processes.In addition, α Fe can be do not separated out in a large number in the principal phase of the magnet behind the sintering, the magnet characteristic can be significantly do not reduced.In addition, also can optionally only make coercive force is improved contributive Dy or Tb is main phase grain boundary place partially.In addition; From suppress the viewpoint consideration of residual carbon like this through low-temperature decomposition; The preferred low-molecular-weight organo-metallic compound (organo-metallic compound that for example, is made up of the alkyl of carbon number 2～6) that uses is as the organo-metallic compound that is added among the present invention.
(based on the embodiment of the condition of calcination processing in the hydrogen and the comparative studies of comparative example)
Figure 17 is the figure of the carbon amount [weight %] in the permanent magnet change calcining heat condition of comparative example 4,5 of a plurality of permanent magnets represent to make with to(for) embodiment 4.What represent among Figure 17 in addition, is that hydrogen and helium quantity delivered in will calcining is set at 1L/ minute and keeps 3 hours result.
Shown in figure 17, compare with the situation of in He atmosphere and vacuum atmosphere, calcining, can find out that the situation of in hydrogen atmosphere, calcining can reduce the carbon amount in the magnet particle more significantly.In addition, as can beappreciated from fig. 17, be high temperature if make in hydrogen atmosphere the calcining heat when ferromagnetic powder calcined, then the carbon amount further significantly reduces, and particularly through being set at 400 ℃～900 ℃, can make the carbon amount be lower than 0.2 weight %.
In addition; In the foregoing description 1～4 and the comparative example 1～5; Use the permanent magnet of making through the operation of [manufacturing approach 2 of permanent magnet], still, even use the permanent magnet of the operation manufacturing through [manufacturing approach 1 of permanent magnet] also can obtain same result.
As stated, in the permanent magnet 1 of this execution mode and the manufacturing approach of permanent magnet 1, adding is added with M-(OR) in the micropowder of the neodium magnet that obtains in pulverizing xThe organo-metallic compound solution of the organo-metallic compound that (in the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x be an integer arbitrarily) represented makes organo-metallic compound be attached to the particle surface of neodium magnet equably.Then, the formed body that powder pressing is obtained kept several hours down at 200 ℃～900 ℃ in hydrogen atmosphere, carried out calcination processing in the hydrogen thus.Then, make permanent magnet 1 through carrying out vacuum-sintering or pressure sintering.Thus, even add Dy or Tb, also can make the Dy of interpolation or the grain boundary place that Tb is magnet partially effectively than prior art less amount.As a result, can reduce the use amount of Dy or Tb, suppress the decline of residual magnetic flux density, and can fully improve coercive force through Dy or Tb.In addition, compare, can more easily carry out decarburization, need not to worry because carbon contained in the magnet behind the sintering causes coercive force decline with the situation of adding other organo-metallic compound, and can be with magnet integral body sintering densely.
In addition, Dy that magnetic anisotropy is high or Tb retrodeviate the grain boundary place that is magnet at sintering, therefore are the Dy at grain boundary place or the generation that Tb suppresses the reverse magnetic domain of grain boundary partially, therefore can improve coercive force.In addition, the addition of Dy or Tb lacks than prior art, therefore can suppress the decline of residual magnetic flux density.
In addition; Magnet through being added with organo-metallic compound is calcined in hydrogen atmosphere before sintering; The carbon that thereby the organo-metallic compound thermal decomposition is burnt in advance contain in the loss of excitation iron particle (reducing the carbon amount), thereby in sintering circuit, form carbide hardly.As a result, can not produce the space between mutually, and can magnet integral body sintering densely can be prevented that coercive force from descending at the principal phase of the magnet behind the sintering and grain boundary.In addition, do not separate out a large amount of α Fe in the principal phase of the magnet behind the sintering, can significantly not reduce the magnet characteristic.
In addition; If the organo-metallic compound that use the organo-metallic compound that is made up of alkyl, more preferably is made up of the alkyl of carbon number 2～6 is as the special organo-metallic compound that adds; When then in hydrogen atmosphere, calcining ferromagnetic powder or formed body, can carry out the thermal decomposition of organo-metallic compound at low temperatures.Thus, can more easily carry out the thermal decomposition of organo-metallic compound to whole ferromagnetic powders or formed body integral body.
In addition; Operation with ferromagnetic powder or formed body calcining; Owing to, therefore can the carbon that contained in the magnet particle be burnt and lose more than the necessary amount through in 200 ℃～900 ℃, more preferably 400 ℃～900 ℃ temperature range, keeping the scheduled time to carry out formed body especially.
The result; Therefore the carbon amount that residues in behind the sintering in the magnet is lower than 0.2 weight %, more preferably less than 0.1 weight %, can not produce the space at the principal phase of magnet and grain boundary between mutually; And can make magnet integral body become the state of dense sintering, can prevent that residual magnetic flux density from descending.In addition, α Fe can be do not separated out in a large number in the principal phase of the magnet behind the sintering, the magnet characteristic can be significantly do not reduced.
In addition, in second manufacturing approach, pulverous magnet particle is calcined especially, therefore compared, can more easily carry out the thermal decomposition of organo-metallic compound whole magnet particles with the situation that the magnet particle after being shaped is calcined.That is, can reduce carbon amount in the calcined body more reliably.In addition, handle, can reduce the activity degree of the calcined body of activation through calcination processing through after calcination processing, carrying out dehydrogenation.Thus, can prevent that the magnet particle combines with oxygen thereafter, thereby residual magnetic flux density or coercive force are descended.
In addition, carry out the dehydrogenation treatment procedures through in 200 ℃～600 ℃ temperature range, keeping the scheduled time to carry out ferromagnetic powder, even therefore in carrying out hydrogen, generate the high NdH of activity degree in the Nd base magnet after the calcination processing 3Situation under, can not have to change into the low NdH of activity degree residually yet 2
In addition, the invention is not restricted to said embodiment, it is obvious that, in the scope that does not break away from main idea of the present invention, can carry out various improvement, distortion.
In addition, the condition that is not limited to put down in writing in the foregoing description such as the pulverization conditions of ferromagnetic powder, kneading condition, calcination condition, dehydrogenation condition, sintering condition.
In addition, in the foregoing description 1～4, use normal propyl alcohol dysprosium, ethanol dysprosium or ethanol terbium as the organo-metallic compound that contains Dy or Tb that adds in the ferromagnetic powder, still, so long as M-(OR) xThe organo-metallic compound that (in the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x be an integer arbitrarily) represented then also can be other organo-metallic compound.For example, also can use organo-metallic compound that constitutes by the alkyl of carbon number more than 7 or the organo-metallic compound that constitutes by the substituting group that comprises the hydrocarbon beyond the alkyl.
Label declaration
1 permanent magnet
10Nd crystal grain
11Dy layer (Tb layer)
91 principal phases
92 grain boundary phases
93 α Fe phases

Claims (7)

1. a permanent magnet is characterized in that, through following operation manufacturing:
With the magnet raw material pulverizing is the operation of ferromagnetic powder,
Through adding the organo-metallic compound that following structural formula is represented in the ferromagnetic powder that obtains in said pulverizing, make said organo-metallic compound be attached to the operation of the particle surface of said ferromagnetic powder,
M-(OR) x
In the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x is integer arbitrarily,
Through the said ferromagnetic powder that particle surface is attached with said organo-metallic compound be formed into body operation and
Operation with said formed body sintering.
2. permanent magnet as claimed in claim 1 is characterized in that,
Form the metal of said organo-metallic compound, retrodeviate the grain boundary place that is said permanent magnet at sintering.
3. according to claim 1 or claim 2 permanent magnet is characterized in that,
R in the said structural formula is an alkyl.
4. permanent magnet as claimed in claim 3 is characterized in that,
R in the said structural formula is any one in the alkyl of carbon number 2～6.
5. the manufacturing approach of a permanent magnet is characterized in that, comprises following operation:
With the magnet raw material pulverizing is the operation of ferromagnetic powder,
Through adding the organo-metallic compound that following structural formula is represented in the ferromagnetic powder that obtains in said pulverizing, make said organo-metallic compound be attached to the operation of the particle surface of said ferromagnetic powder,
M-(OR) x
In the formula, M is Dy or Tb, and the substituting group of R for being made up of hydrocarbon can be straight or branched, and x is integer arbitrarily,
Through the said ferromagnetic powder that particle surface is attached with said organo-metallic compound be formed into body operation and
Operation with said formed body sintering.
6. the manufacturing approach of permanent magnet as claimed in claim 5 is characterized in that, the R in the said structural formula is an alkyl.
7. the manufacturing approach of permanent magnet as claimed in claim 6 is characterized in that, the R in the said structural formula is any one in the alkyl of carbon number 2～6.
CN201180003903XA 2010-03-31 2011-03-28 Permanent magnet and manufacturing method for permanent magnet Pending CN102511069A (en)

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